Fluid separation membrane

Abstract

The present invention provides a fluid separation membrane which has a fibrous porous support layer coated on the surface with a separation function layer, a particle layer being at least partially interposed between the porous support layer and the separation function layer, and the particle layer containing fibrous particles and / or plate-shaped particles. The present invention can provide a fluid separation membrane having high separation performance and long-term stability.

Description

fluid separation membrane

[0001] The present invention relates to a fluid separation membrane.

[0002] Membrane separation is used as a method to selectively separate and purify specific components from various mixed gases and liquids. Membrane separation is attracting attention because it is an energy-efficient method compared to other fluid separation methods such as distillation.

[0003] For example, in natural gas refining plants, it is necessary to separate and remove carbon dioxide, an impurity contained in methane gas, the main component. When applying membrane separation to this purpose, it is required to maintain high separation performance over a long period of time even in an environment exposed to high gas injection pressures of several MPa or more. Furthermore, membrane separation methods are beginning to be used in the chemical industry to separate water, an impurity contained in alcohol or acetic acid. Even in these applications, fluid separation membranes with high separation performance and long-term stability are required from the perspectives of productivity and quality stability. Porous materials such as alumina, silica, and metal oxides are known as supports for fluid separation membranes, and controlling the pore diameter to the desired size depending on the application is important. There is a trade-off between a small pore diameter resulting in reduced fluid diffusivity and a large pore diameter resulting in reduced compressive strength. Porous materials are used in a variety of applications, but when used in separation membranes, it is known that the pore diameter of the porous material determines the separation characteristics. In particular, when using a porous material as a support for a separation membrane, the presence of large pores on the surface of the porous material can easily cause defects such as pinholes in the separation functional layer formed on the surface, resulting in a decrease in the yield of the separation membrane. On the other hand, when the pores of a porous material are made denser, the membrane production efficiency improves, but the permeation resistance increases, resulting in a problem of reduced performance of the separation membrane.

[0004] Against this background, a method has been proposed to achieve both compressive strength and fluid diffusivity by layering a particle layer with pores smaller than the pore diameter of a porous support layer with a large pore diameter.

[0005] Patent Document 1 proposes a method for forming a thin separation membrane without defects such as pinholes by depositing a particle layer consisting of an aggregate of spherical silica particles with a uniform particle size on the surface of a porous support and forming a smooth surface while controlling the pore diameter. On the other hand, Patent Document 2 proposes a porous carbon fiber that is flexible and has excellent heat and chemical resistance, and is expected to be used as a porous support layer that can be used under harsh conditions such as high-temperature operation and impurity environments while preventing breakage during handling.

[0006] JP 2002-293656 A

[0007] When a spherical particle layer as described in Patent Document 1 is laminated on a porous support layer characterized by the flexibility described above in order to improve membrane formability and fluid diffusivity, the weak adhesive strength resulting from the small contact area between the spherical particles prevents the layer from following the bending deformation of the porous support layer, resulting in peeling.In addition, if an attempt is made to suppress peeling, the flexibility of the particle layer is lost, causing fractures including the porous support layer, making continuous production impossible and reducing productivity.Furthermore, peeling is likely to progress at the interface between the porous support layer and the particle layer, causing destruction of the entire porous material starting from the peeled portion, and there are other practical problems, such as making it impossible to arbitrarily control the pore diameter.In addition, fluid separation membranes formed on porous materials can be damaged by pressure fluctuations over time during operation.

[0008] Therefore, an object of the present invention is to provide a porous material that is flexible, has excellent productivity, and is capable of achieving both compressive strength and fluid diffusivity, and a fluid separation membrane that has high separation performance and long-term stability.

[0009] The present invention, which solves the above-mentioned problems, has the following configuration.

[0010] A fluid separation membrane having a fibrous porous support layer whose surface is coated with a separation functional layer, and a particle layer interposed at least partially between the porous support layer and the separation functional layer, the particle layer containing fibrous particles and / or tabular particles.

[0011] The present invention provides a porous material that is flexible, has excellent productivity, and is capable of achieving both compressive strength and fluid diffusivity. Furthermore, by using the porous material of the present invention as a support, a fluid separation membrane with high separation performance and long-term stability can be provided.

[0012] The present invention is a fluid separation membrane having a fibrous porous support layer whose surface is coated with a separation functional layer, and a particle layer interposed at least partially between the porous support layer and the separation functional layer, the particle layer containing fibrous particles and / or tabular particles.

[0013] <Porous Support Layer> The porous material of the present invention has a porous support layer and a particle layer.

[0014] The porous support layer in the porous material of the present invention is not particularly limited as long as it is porous, does not hinder fluid permeation, and has the function of supporting the particle layer, and conventionally known materials can be appropriately selected. Examples of materials suitable for the porous support layer include materials with closed cells derived from a sea-island structure, materials with a structure in which multiple particles are connected, materials such as woven fabrics and nonwoven fabrics in which fibrous materials are folded and appropriately bonded as necessary, and materials with a continuous porous structure in which the voids and the material constituting the support are continuous with each other. These materials are preferably selected from the perspective of not hindering fluid permeation and functioning as a support for the separation function layer. Among these, materials with a continuous porous structure are more preferred because the voids and the material constituting the porous support layer are continuous with each other and the curvature of the interface is lower than in porous support layers with connected particles. This means that they do not hinder fluid permeation, and the material constituting the porous support layer has a high stress dispersion effect, resulting in increased compressive strength.

[0015] The material of the porous support layer is not particularly limited and can be selected from conventionally known materials. Examples of such materials include inorganic materials such as alumina, silica, cordierite, zirconia, titania, Vycor glass, zeolite, magnesia, carbon, and sintered metal; organic materials containing at least one polymer selected from the group consisting of homopolymers and copolymers of polysulfone, polyethersulfone, polyamide, polyester, cellulose-based polymer, vinyl polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide; and carbon materials obtained by carbonizing organic materials made from carbonizable resins. Porous versions of these materials can also be used. Examples of carbonizable resins include polyphenylene oxide, polyvinyl alcohol, polyacrylonitrile, phenolic resin, wholly aromatic polyester, unsaturated polyester resin, alkyd resin, melamine resin, urea resin, polyimide resin, diallyl phthalate resin, lignin resin, and urethane resin. Two or more of these materials may also be used. The material constituting the porous support layer is preferably an inorganic material from the viewpoints of heat resistance, chemical resistance, and mechanical strength. When the particles contained in the particle layer and the material are made of the same material, this is preferred because the particle layer and the porous support layer have similar chemical properties and therefore have excellent interfacial adhesion.

[0016] If the element that is most abundant in terms of numbers among the elements constituting the porous support layer of the present invention, excluding halogen elements and oxygen, is defined as element A, then element A constituting the porous support layer is preferably the same as element B constituting the fibrous particles and / or tabular particles contained in the particle layer described below. When element A and element B are the same, when an interface is formed between the porous support layer and the fibrous particles and / or tabular particles, the adhesion between the fibrous particles and / or tabular particles and the porous support layer at the interface is good, and the porous material as a whole tends to be free from fracture at the peeled portions and to have improved strength, which is preferable.

[0017] A fibrous material is used as the porous support layer, but there are no particular limitations as long as it is fibrous, and it can be in any shape.

[0018] The cross-sectional shape of the fiber is not limited in any way and can be any shape, including round, triangular, or other multilobal cross-sections, flat, or hollow cross-sections. In particular, a porous support layer having a hollow cross-section, i.e., a porous support layer having a hollow fiber configuration, is preferred because it can provide pressure resistance while suppressing pressure loss when a fluid flows through the porous support layer. A higher hollowness of the hollow fiber is preferred because it reduces pressure loss, particularly in the fiber axial direction, and does not interfere with fluid flow. A lower hollowness is preferred because it can increase compressive strength in the fiber cross-sectional direction. From these perspectives, a hollowness that can balance these two is preferably in the range of 10 to 90%, and more preferably in the range of 20 to 60%. The hollow fiber may have a single hollow portion or multiple hollow portions.

[0019] When the porous support layer has a hollow fiber form, the outer diameter of the hollow fiber is not particularly limited and can be determined arbitrarily taking into consideration strength, flexibility, and the like depending on the application. However, when considering handleability such as strength, the outer diameter of the hollow fiber porous support layer is preferably 0.02 mm or more, and from the viewpoint of flexibility, the outer diameter of the hollow fiber porous support layer is preferably 50 mm or less.

[0020] The porosity of the porous support layer is preferably 10% or more, more preferably 25% or more, because a larger porosity reduces fluid pressure loss and makes it easier to secure multiple highly efficient flow paths. On the other hand, the smaller the porosity, the better the handling properties such as mechanical strength, so the porosity is preferably 80% or less, more preferably 70% or less.

[0021] Here, the porosity of the porous support layer refers to the value calculated by setting the region of interest required for calculation from an image observed by three-dimensional microscopy, defining the volume of the region of interest as A and the volume of the voids in the region of interest as B, using the following formula:

[0022] Porosity (%) = B / A x 100 Three-dimensional microscope photography is not particularly limited as long as it allows for the separation and observation of the solid and void portions that make up the porous support layer, but it is preferable to appropriately select an analytical technique that allows for the separation, observation, and analysis of the solid and void portions as electronic information, such as slice and view, in which a cross section is cut out with an ion beam and then continuously observed with a scanning electron microscope, or a method of applying computer tomography using a transmission X-ray or electron microscope. In this case, if the electron beam contrast between the solid and void portions is weak and observation is difficult, observation was performed after electron staining using an appropriate heavy metal or the like.

[0023] <Particle Layer> The particle layer in the porous material of the present invention is defined as being disposed so as to be in contact with at least a portion of the porous support layer, and being interposed therebetween. The shape of the particle layer is not particularly limited, and any shape such as cylindrical, striated, spiral, spherical, or block-like is possible, but a cylindrical particle layer is preferred because it disperses the force applied in the cross-sectional direction and makes it easier to maintain high pressure resistance.

[0024] The particle layer is not particularly limited as long as it is in contact with a portion of the porous support layer. However, if the area of ​​the porous support layer covered by the particle layer is large, the particle layer can control the pore diameter while ensuring fluid diffusivity, and therefore, one preferred embodiment is one in which the entire surface of one side of the porous support layer is covered by the particle layer.

[0025] Here, "arranged so that the particle layer is in contact with at least a portion of the porous support layer" refers to a state in which the particle layer is in contact with at least a portion of the surface of the porous support layer. The particle layer can be arranged to cover the entire surface of the porous support layer, to cover only one surface, or to cover only a portion of the surface. In particular, in the case where the porous material has a separation function layer described below, it is preferable that the surface of the porous support layer on the side where the separation function layer is formed is covered with the particle layer. In other words, in the case of a porous material having a separation function layer, a form in which the porous support layer / particle layer / separation function layer are laminated in this order is preferable.

[0026] In the present invention, the particle layer refers to a layer mainly composed of particles. Here, a particle-based layer refers to a layer in which the total volume of fibrous particles and tabular particles accounts for 5% or more of the total volume of the layer excluding voids, assuming that the volume of the layer excluding voids is 100%. In this case, the portion of the particle layer other than the fibrous particles and / or tabular particles is not particularly limited, but other particles, i.e., particles other than the fibrous particles and tabular particles described below (particles with an aspect ratio of less than 10) or a binder resin may be contained in the particle layer. The binder resin is not particularly limited as long as it has the function of bonding particles together, and conventionally known materials can be appropriately selected. When a separation function layer described below is formed, the inorganic or organic material constituting the separation function layer may be contained in the particle layer. A large volume fraction of the fibrous particles and tabular particles is preferred because it is more likely to cause entanglement between particles, preventing peeling or destruction within the particle layer, between particle layers, and between the particle layer and the porous support layer. When the total volume occupied by the fibrous particles and the tabular particles is 97% or more and 100% or less, pores are particularly easily formed, the fluid permeation resistance can be effectively reduced, and this is preferable from the viewpoint of the permeability of the fluid separation membrane. On the other hand, when particles other than the fibrous particles and tabular particles (particles with an aspect ratio of less than 10) described below are contained in the particle layer, it becomes easier to control the pore size on the particle layer surface, and there is an effect that the fluid separation membrane formed on the particle layer surface has excellent membrane formability. From the above viewpoints, it is also preferable that the total volume occupied by the fibrous particles and the tabular particles is 20% or more and less than 97%.

[0027] The volume occupied by fibrous particles and tabular particles in the layer is analyzed by extracting a three-dimensional image as electronic information using a measurement method that can grasp the three-dimensional shape, such as three-dimensional microscopy. To distinguish between fibrous particles and tabular particles and other parts, it is preferable to appropriately select an analytical method that can separate, observe, and analyze them as electronic information. In this case, if the electron beam contrast between the fibrous particles and tabular particles and other parts is weak and observation is difficult, electron staining is performed using a heavy metal or the like before observation. The extracted fibrous particles and / or tabular particles are separated by an appropriate method, and the least squares method is applied to each particle to approximate it as an ellipsoid. The volume occupied by fibrous particles and tabular particles is calculated by setting the volume of the observed three-dimensional image where the number of particles of interest exceeds 200, and calculating the volume fraction of particles with an aspect ratio of 10 or more.

[0028] The particle layer of the present invention contains fibrous particles and / or tabular particles. The fibrous particles and / or tabular particles of the present invention refer to particles with an aspect ratio of 10 or more. Here, the term "fibrous particles" refers to particles having one major axis, where Lb is the shortest of the three diameters of an ellipsoid obtained from the particle (three diameters that pass through the center of the ellipsoid and intersect at right angles), and the major axis is the diameter that has an aspect ratio of 10 or more to Lb. The term "tabular particles" refers to particles having two major axes, where Lb is the diameter that has an aspect ratio of 10 or more to Lb.

[0029] Here, the three diameters are measured from the three-dimensional data of a particle extracted as digital data using a measurement method that can grasp the three-dimensional shape of a single particle in the particle layer, such as three-dimensional microscopic photography, and the ratio of the length Lb of the shortest diameter to the length La of the longest diameter (La / Lb) is defined as the aspect ratio.

[0030] The aspect ratio of fibrous particles and / or tabular particles is calculated by taking 10 random particles from particles with an La / Lb of 10 or more, calculating the ratio of Lb to La (La / Lb) for each particle, and averaging the 10 values. The longest length Ll of fibrous particles and / or tabular particles is calculated as the average value of the La values ​​of the 10 particles selected when calculating the aspect ratio. The shortest length Ls of fibrous particles and / or tabular particles is calculated as the average value of the Lb values ​​of the 10 particles selected when calculating the aspect ratio.

[0031] The longer the maximum length Ll, the more easily entanglement occurs between particles, and peeling or destruction within the particle layer, between particle layers, or between the particle layer and the porous support layer can be prevented. In particular, when an interface is formed between the porous support layer and the fibrous particles and / or tabular particles, the adhesion between the fibrous particles and / or tabular particles and the porous support layer at the interface is good, and destruction at the peeled portion of the entire porous material tends to be prevented, and the strength tends to be improved. Furthermore, the smaller Ll, the better the handleability during particle layer formation, and in particular, when the particle layer is formed using a liquid, it is preferable from the viewpoint of being able to form the particle layer while maintaining the fluidity of the liquid. From these viewpoints, Ll is preferably 0.05 μm or more and 1000 μm or less, and more preferably 1 μm or more and 100 μm or less.

[0032] The higher the aspect ratio of the fibrous particles and / or tabular particles, the more likely interparticle entanglement occurs, preventing peeling or destruction within the particle layer, between particle layers, and between the particle layer and the porous support layer. In particular, when an interface is formed between the porous support layer and the fibrous particles and / or tabular particles, the adhesion between the fibrous particles and / or tabular particles and the porous support layer at the interface is good, preventing fracture at the peeled portion of the porous material as a whole and tending to improve strength. Furthermore, the lower the aspect ratio, the better the handleability during particle layer formation. In particular, when a particle layer is formed using a liquid, the particle layer can be formed while maintaining the fluidity of the liquid. From these perspectives, the aspect ratio of the fibrous particles and / or tabular particles in the particle layer is preferably in the range of 20 to 10,000, more preferably 100 to 2000.

[0033] The fraction of fibrous particles and / or tabular particles is not particularly limited, but since fibrous particles are advantageous in terms of fluid diffusibility because they easily form pores, it is preferable that the volume fraction of fibrous particles be large relative to the total volume of fibrous particles and tabular particles.

[0034] The fibrous particles and / or tabular particles preferably contain at least one type selected from the group consisting of cellulose nanofibers, carbon nanohorns, carbon nanoribbons, carbon nanotubes, graphene, and graphene oxide, as described below.

[0035] The fibrous particles constituting the particle layer of the present invention have a tendency to orient in the direction of liquid flow during the formation of the particle layer, particularly when a liquid application process is employed, and this orientation of the fibrous particles is preferable because it exhibits reinforcement in a specific direction, particularly in the fiber axis direction, and improves bending rigidity in the direction perpendicular to the fiber axis. Examples of additives having a fibrous shape that are candidates for the fibrous particles include whiskers, cellulose nanofibers, carbon nanohorns, carbon nanoribbons, and carbon nanotubes. Considering the preferred range of Ls described below, cellulose nanofibers, carbon nanohorns, carbon nanoribbons, and carbon nanotubes are preferred.

[0036] On the other hand, the tabular particles constituting the particle layer of the present invention have a tendency to be plane-oriented in the direction of liquid flow when forming the particle layer, particularly when a liquid coating process is employed, and when the orientation direction is the MD direction, they are likely to exhibit reinforcement in both the MD and TD directions, which is preferable. Examples of additives having a tabular shape that are candidates for the tabular particles include graphene, graphene oxide, talc, and mica, and considering the preferred Ls range described below, graphene and graphene oxide are preferred. The material of the particles is not particularly limited as long as it can exhibit the above-mentioned effects, and may contain carbon, oxygen, nitrogen, boron, sulfur, silicon, etc., and may also contain alkali metals, alkaline earth metals, etc.

[0037] The fibrous particles and / or tabular particles of the present invention may be used alone or in combination of two or more kinds. Depending on the application, etc., other particles, i.e., particles having an aspect ratio of less than 10, may be contained within a range that does not impair the object of the present invention, but the content of particles having an aspect ratio of less than 10 is preferably less than 50% by volume, more preferably less than 20% by volume, of the total of all particles (i.e., the total of particles having an aspect ratio of 10 or more and particles having an aspect ratio of less than 10) 100% by volume.

[0038] The size of the fibrous particles and / or tabular particles in the particle layer is not particularly limited, but it is preferable that the shortest length Ls of the fibrous particles and / or tabular particles is 0.4 nm or more and 10 μm or less. When Ls is 0.4 nm or more, handling is easy while ensuring a sufficient specific surface area. On the other hand, when Ls is 10 μm or less, the specific surface area is large, adhesion to the porous support layer is good, and the strength of the porous material is improved. In addition, since the particles have excellent flexibility, the surface of the particle layer formed so that a part of it contacts the porous support layer is easily smoothed, and when used as a fluid separation membrane, the membrane formability of the separation function layer is improved. From the above viewpoints, it is more preferable that the length Ls of the shortest diameter of the particles is 1 nm or more and 100 nm or less.

[0039] The porosity of the particle layer is not particularly limited, but a small porosity increases the adhesive strength between particles and improves peel resistance, so it is preferably 3% or more, more preferably 5% or more. A large porosity reduces pressure loss against the fluid, so it is preferably 50% or less, more preferably 30% or less. Here, the porosity of the particle layer refers to the porosity calculated by setting a region of interest required for calculation from an image observed by three-dimensional microscopy, where A is the volume of the region of interest and B is the volume of the voids in the region of interest, using the following formula:

[0040] Porosity (%) = B / A x 100. Three-dimensional microscopy is not particularly limited as long as it can separate and observe the solid and void portions that make up the particle layer. However, it is preferable to appropriately select an analytical method that can separate, observe, and analyze the solid and void portions as electronic information, such as slice-and-view, in which a cross section is cut with an ion beam and then continuously observed with a scanning electron microscope, or a method using transmission X-ray or electron microscopes to apply computed tomography. In this case, if the electron beam contrast between the solid and void portions is weak and observation is difficult, electron staining using heavy metals or the like is performed before observation. Note that, to account for variation, data containing 10 or more particles is used. If 10 or more particles are not present in one data point, data obtained from another observation field is added, and a particle layer containing a total of 10 or more particles is observed to determine the volume percent.

[0041] The thickness of the particle layer of the present invention is not particularly limited, but a thicker layer is preferable because it is more resistant to damage by external forces and has excellent durability, while a thinner layer is preferable because it can reduce fluid permeation resistance and improve fluid diffusibility. From these perspectives, the thickness of the particle layer is preferably in the range of 0.2 μm to 100 μm, and more preferably in the range of 0.5 μm to 10 μm. Here, the thickness of the particle layer is defined by measuring the thickness of the thinnest part constituting the particle layer using a microscope or the like when a cross section for observation is formed from the porous material, and is calculated as the average thickness obtained by analyzing 10 points on the cross section of the porous material.

[0042] <Fluid separation membrane> The porous material of the present invention can be used as a support and a separation functional layer formed in a layered form so that at least a portion of the layer is in contact with the particle layer, thereby making it possible to use it as a fluid separation membrane. That is, the fluid separation membrane of the present invention is a fluid separation membrane having a separation functional layer and the porous material of the present invention, characterized in that the particle layer and the separation functional layer are arranged so as to be in contact with each other. In the fluid separation membrane of the present invention, the porous material ensures fluid diffusibility and durability, preventing breakage during actual use and enabling long-term stable operation. In addition, even when high pressure is applied, the porous support layer and the particle layer each distribute stress, and the porous material as a whole bears the pressure, making it possible to operate in a high-pressure environment.

[0043] The separation functional layer that is preferably combined with the porous material of the present invention is in contact with the particle layer of the porous material. When the separation functional layer is in contact with the particle layer, it can efficiently distribute the internal stress to the particle layer when subjected to an external force such as pressure, thereby improving pressure resistance. Furthermore, when the particle layer and the separation functional layer are in contact, external forces such as bending can be released due to the frictional force at the interface between the two, and peeling between the particle layer and the separation functional layer can also be expected to be suppressed.

[0044] The separation functional layer is not particularly limited as long as it is a material that has the function of separating fluids, and conventionally known organic or inorganic materials can be appropriately selected. The organic material is not particularly limited, but examples thereof include aromatic polyimide, cellulose acetate, polysulfone, aromatic polyamide, polyamideimide, polyetherimide, polyethersulfone, polyacrylonitrile, polyphenylene sulfide, polyphenylene oxide, polyetheretherketone, polytetrafluoroethylene, polyvinylidene fluoride, poly(1-trimethylsilylpropyne), polydimethylsiloxane, polyvinyltrimethylsilane, poly(4-methylpentene), ethylcellulose, natural rubber, poly(2,6-dimethylphenylene oxide), low-density polyethylene, high-density polyethylene, styrene, polyethyl methacrylate, polycarbonate, polyester, aliphatic polyamide, polyvinyl alcohol, various polyethers such as polyethylene glycol, polymethacrylic acid, polymethyl methacrylate, various microporous polymers (PIMs), various thermal transition polymers (TR polymers), and copolymers or mixtures thereof. The separation functional layer is preferably an inorganic material because inorganic materials tend to have high heat resistance and chemical resistance and can stably exhibit the separation performance of the fluid separation membrane over the long term. The inorganic material is not particularly limited, but examples include carbon materials using the organic materials as precursors, zeolites, silica, and metal-organic frameworks. From the perspective of easily controlling the carbon element ratio (described below), the separation functional layer is preferably a carbide using an organic material as a precursor, such as a material obtained by firing a polymer material containing at least one of the thermoplastic resins and thermosetting resins. It is particularly preferable to select phenolic resins, polyacrylonitrile, polyimides, etc.

[0045] The material of the separation functional layer is not particularly limited, but the carbon element ratio is preferably 70 atomic% or more and 99.5 atomic% or less. The larger the carbon element ratio X of the matrix, the better the membrane performance, chemical resistance, and heat resistance, so it is preferable, and 80 atomic% or more is more preferable. On the other hand, the lower the carbon content, the more flexible and resistant to breakage the matrix becomes, thereby improving long-term durability, so the carbon element ratio X of the matrix is ​​more preferably 92 atomic% or less. The constituent elements other than carbon of the separation functional layer are not particularly limited, and may contain hydrogen, oxygen, nitrogen, boron, sulfur, silicon, etc., and may also contain alkali metals, alkaline earth metals, etc. The above element ratios can be analyzed using energy dispersive X-ray spectroscopy in combination with an electron microscope.

[0046] The elastic modulus of the separation functional layer is preferably 10 GPa or more and 300 GPa or less. A high elastic modulus of the separation functional layer exhibits the effect of preventing destruction of the separation functional layer, thereby preventing breakage during operation as a gas separation membrane and enabling stable use for a long period of time. On the other hand, the lower the elastic modulus, the more flexibly the layer deforms, and the more easily instantaneous impact forces can be absorbed, so the elastic modulus is more preferably 15 GPa or more and 200 GPa or less. The above elastic modulus can be determined by various analytical methods, but can be analyzed using a method for calculating the elastic modulus using Hertz's contact theory using the nanoindentation method.

[0047] Furthermore, it is preferable for the separation functional layer to be in a form in which some of the inorganic or organic materials constituting the separation functional layer are composited with a particle layer of a porous material, as this can enhance the effect of suppressing peeling when external forces such as pressure or bending are applied as a fluid separation membrane. Furthermore, the less composite the layer is, the more preferable it is because it can maintain high fluid diffusion in the particle layer. From these perspectives, the composite ratio of the separation functional layer is preferably in the range of 1% to 50% to achieve an excellent balance between the two, and more preferably 10% to 40%. Here, the composite ratio of the separation functional layer refers to the ratio calculated by setting the region of interest required for calculation from an image observed by three-dimensional microscopy, and using the following formula: Vm, where Vp is the volume of the separation functional layer in the region of interest, Vp is the volume of the particles constituting the particle layer, and Va is the volume of the voids.

[0048] Composite ratio (%) of separation functional layer = (Vm / (Vm + Vp + Va)) × 100. The three-dimensional microscope photography is not particularly limited as long as it separates the solid and void portions that make up the particle layer, and further separates and observes the solid portions into particles and the separation functional layer. However, it is preferable to appropriately select an analytical method that can separate, observe, and analyze the separation functional layer, particles, and void portions as electronic information, such as slice and view, in which a cross section is cut with an ion beam and continuously observed with a scanning electron microscope, or a method using transmission X-ray or electron microscopes and computer tomography. In this case, if the electron beam contrast between the solid and void portions is weak and observation is difficult, electron staining using heavy metals or the like was performed before observation. Note that, to account for variability, data containing 10 or more particles was used. If there are not 10 or more particles in one data set, data obtained from another observation field was added, and the particle layer containing a total of 10 or more particles was observed to determine the volume percent.

[0049] The pore diameter of the separation functional layer can be appropriately selected depending on the substance to be separated, but when the substance to be separated is a fine particle or a high molecular weight substance contained in a liquid, the pore diameter of the separation functional layer is preferably 1 nm to 10 μm. When the substance to be separated is a gas, the pore diameter of the separation functional layer is preferably 0.2 nm to 2 nm.

[0050] The fluid separation membrane of the present invention, which combines the porous material and a separation functional layer, is fibrous, but has the advantage of being able to have a larger membrane area per unit volume compared to a film-like membrane. In addition, since it has high resistance to forces applied in the cross-sectional direction, it is possible to operate it at high pressure, which is preferable because it enables highly efficient membrane separation.

[0051] The cross-sectional shape of the fibers of the fluid separation membrane of the present invention is not limited in any way and can be any shape, such as a round cross-section, a multi-lobed cross-section such as a triangular cross-section, a flat cross-section, or a hollow cross-section. In particular, a fluid separation membrane having a hollow cross-section, i.e., a hollow fiber-like configuration, is preferred because it allows for pressure resistance while controlling the flow of the supplied fluid and the separated fluid. A higher area ratio of the cross-sectional area X of the hollow portion to the cross-sectional area Y of the hollow fiber (hollow area ratio: 100 × X / Y) reduces pressure loss and prevents fluid flow, while a lower ratio increases pressure resistance. From these perspectives, the hollow area ratio is preferably in the range of 5 to 70%. Here, the cross-sectional area Y of the hollow fiber is the cross-sectional area including the cross-sectional area X of the hollow portion. Furthermore, the hollow fiber may have multiple hollow portions, in which case the sum of the cross-sectional areas of the hollow portions is taken as the cross-sectional area X of the hollow portions.

[0052] The method for producing a porous material of the present invention preferably includes a step of contacting a porous support layer with a slurry solution containing fibrous particles and / or tabular particles to form a particle layer containing fibrous particles and / or tabular particles on the outer surface of the porous support layer. Examples of methods for contacting the porous support layer with the slurry solution include dip coating, spray coating, nozzle coating, and liquid film transfer, and can be appropriately selected depending on the type of slurry solution. Furthermore, a solvent and a dispersant can be appropriately used in the slurry solution.

[0053] The method for producing a fluid separation membrane of the present invention preferably includes a step of coating the porous material of the present invention with a solution containing a fluid separation membrane material and / or a fluid separation membrane precursor. Examples of coating methods include dip coating, spray coating, nozzle coating, and liquid membrane transfer, and can be appropriately selected depending on the material of the fluid separation membrane. Furthermore, solvents and additives can be used as appropriate during coating.

[0054] The separation membrane module of the present invention is a separation membrane module having the fluid separation membrane of the present invention housed in a case, and more specifically, a form in which the fluid separation membrane of the present invention is housed in a case. The separation membrane module controls the flow of fluids and has flow channels formed therein for guiding fluids that have permeated the fluid separation membrane. It is preferable to use a case or a sealant for the purpose of controlling these fluid flows. The material of the case is not particularly limited, but is preferably selected appropriately depending on the usage environment, such as pressure resistance and heat resistance. Examples include metal, resin, carbon, and composites thereof. The gas separation process to which the separation membrane module of the present invention can be applied is not particularly limited, but by disposing the separation membrane module of the present invention in at least a part of the process, it can be suitably used in processes requiring high separation performance and long-term stability. The separation membrane module of the present invention is disposed in at least a part of the process. Examples of processes requiring high separation performance and long-term stability include carbon dioxide separation and storage systems from exhaust gases of power plants, blast furnaces, etc., removal of sulfur components from gasified fuel gas in integrated coal gasification combined cycle power generation, purification of biogas and natural gas, and purification of hydrogen from organic hydrides.

[0055] A method for producing a fluid that at least partially uses such a gas separation process may include a separate purification step or an additional step before or after the purification step in the separation membrane module of the present invention, or may produce a fluid by mixing with a purified fluid purified in a different purification step. Examples of separate purification steps or different purification steps include distillation, adsorption, and absorption. Examples of additional steps include component adjustment by mixing with another fluid.

[0056] The fluid obtained by the production method of the present invention is purified using the separation membrane module of the present invention, which combines high separation performance with long-term stability, and therefore energy consumption in the above-mentioned additional process is reduced, making it suitable for use in various industrial applications as a fluid with low environmental impact.

[0057] (Frequency of Peeling of Particle Layer) A 1 m section of the porous material obtained by adhering a particle layer to the outer surface of the porous support layer was sampled in the longitudinal direction of the fiber and observed under a microscope to count the number of peeled particle layer locations. The exposed portion of the porous support layer on the outer surface was determined to be the peeled location. (Measurement of Gas Permeation Rate) Modules were fabricated using the fluid separation membranes obtained in each Example and Comparative Example, and the gas permeation rate Q was measured. Carbon dioxide and methane were used as the measurement gases, and the pressure change per unit time of the permeation side for carbon dioxide and methane was measured using an external pressure method at a measurement temperature of 25°C in accordance with the pressure sensor method of JIS K7126-1 (2006). The pressure difference between the supply side and the permeation side was set to 0.11 MPa.

[0058] Next, the gas permeation rate Q was calculated using the following formula: The ratio of the gas permeation rates Q of the individual components was defined as the separation factor α. Here, the membrane area was calculated from the outer diameter and length of the region contributing to gas permeation.

[0059] Gas permeation rate Q = [permeation gas amount (mol)] / [membrane area (m ２ ) × time (s) × pressure difference (Pa) When the gas permeation rate Q of carbon dioxide is 30 nmol / (m ２ .Pa.s) or more is "large"; ２ ・Pa・s) or more 30nmol / (m ２ If the gas permeation rate Q is less than 20 nmol / (m ２・Pa ・s), it was judged as "small". (Separation Factor of Carbon Dioxide and Methane) The gas permeation rates Q of carbon dioxide and methane were measured, and the separation factor of carbon dioxide and methane was calculated as (permeation rate of carbon dioxide) / (permeation rate of methane). When the separation factor of carbon dioxide and methane was 30 or more, it was judged as "best", when the separation factor was 25 or more but less than 30, it was judged as "excellent", when the separation factor was 20 or more but less than 25, it was judged as "good", when the separation factor was 10 or more but less than 20, it was judged as "passable", and when the separation factor was less than 10, it was judged as "poor". (Production Example 1) 10 parts by weight of polyacrylonitrile (PAN) (MW 150,000) manufactured by Polysciences, 10 parts by weight of polyvinylpyrrolidone (PVP) (MW 40,000) manufactured by Sigma-Aldrich, and 80 parts by weight of dimethyl sulfoxide (DMSO) manufactured by Fujifilm Wako Pure Chemical Industries were mixed and stirred at 100 ° C. to prepare a spinning dope.

[0060] The obtained spinning dope was cooled to 25° C., and then a concentric triple spinneret was used to simultaneously discharge an 80 wt % aqueous solution of DMSO from the inner tube, the spinning dope from the middle tube, and a 90 wt % aqueous solution of DMSO from the outer tube, and then the spinning dope was introduced into a coagulation bath of pure water at 25° C. and taken up on a roller to obtain a raw fiber. The obtained raw fiber was washed with water and then dried at 25° C. for 24 hours using a circulating dryer to produce a precursor of a hollow fiber-shaped porous carbon membrane.

[0061] The obtained porous carbon membrane precursor was passed through an electric furnace at 250°C and heated in an air atmosphere for 1 hour to perform an infusible treatment, thereby obtaining an infusible yarn. The infusible yarn was then carbonized at a carbonization temperature of 650°C to obtain a porous support layer of Production Example 1 having an outer diameter of 0.3 mm, a hollow area ratio of 44%, and a porosity of 48%. (Example 1) A carbon nanotube (CNT) slurry was applied to the porous support layer of Production Example 1 by dip coating, and then dried at 50°C for 12 hours using a circulating dryer, thereby continuously producing a porous material in which a carbon nanotube (CNT) particle layer was adhered to the outer surface of the porous support layer. As a result of evaluation using the above-mentioned method, no peeling was observed at the interface between the porous support layer and the particle layer.

[0062] The obtained porous material was coated with an aromatic polyimide solution by dip coating, and after removing the solvent, it was dried in a circulation dryer at 50°C for 12 hours to form an aromatic polyimide coating on the particle layer surface of the porous material. Subsequently, the porous material coated with the aromatic polyimide was fired at 700°C in a nitrogen atmosphere to continuously produce a fluid separation membrane.

[0063] As a result of evaluation by the above-mentioned method, the proportion of fibrous particles and / or tabular particles (the proportion of particles with an aspect ratio of 10 or more among the total of particles with an aspect ratio of 10 or more and particles with an aspect ratio of less than 10) was 98% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1623, the longest length Ll was 21.9 μm, the shortest length Ls was 14 nm, the thickness of the particle layer was 1.0 μm, and the porosity of the particle layer was 28%. In addition, the carbon element ratio of the separation functional layer was 83.4 atomic%, the elastic modulus of the separation functional layer was 28 GPa, and the composite proportion of the separation functional layer and the particle layer was 24% by volume.

[0064] The resulting fluid separation membrane had a carbon dioxide gas permeation rate of "high" and a separation factor of carbon dioxide and methane of "excellent." The evaluation results are shown in Table 1. (Example 2) A fluid separation membrane of Example 2 was produced in the same manner as Example 1, except that a slurry of carbon nanotubes (CNT) and carbon black (CB) mixed at a volume ratio of 9:1 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 91% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1590, the longest length Ll was 11.2 μm, the shortest length Ls was 7 nm, the thickness of the particle layer was 0.8 μm, and the porosity of the particle layer was 22%. In addition, the carbon element ratio of the separation functional layer was 83.4 atomic%, the elastic modulus of the separation functional layer was 26 GPa, and the composite ratio of the separation functional layer and the particle layer was 21% by volume.

[0065] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 2 was "medium," and the separation factor between carbon dioxide and methane was "best." The evaluation results are also shown in Table 1. (Example 3) A fluid separation membrane of Example 3 was produced in the same manner as Example 1, except that a slurry in which carbon nanotubes (CNTs) and graphene were mixed at a volume ratio of 1:1 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 98% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1114, the longest length Ll was 9.6 μm, the shortest length Ls was 9 nm, the thickness of the particle layer was 0.9 μm, and the porosity of the particle layer was 26%. The carbon element ratio of the separation functional layer was 83.6 atomic %, the elastic modulus of the separation functional layer was 27 GPa, and the composite ratio of the separation functional layer and the particle layer was 21 volume %.

[0066] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 3 was "medium," and the separation factor between carbon dioxide and methane was "excellent." The evaluation results are also shown in Table 1. (Example 4) A fluid separation membrane of Example 4 was produced in the same manner as Example 1, except that a slurry of carbon nanotubes (CNT) and carbon black (CB) mixed at a volume ratio of 1:4 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 18 volume %, the aspect ratio of the fibrous particles and / or tabular particles was 1756, the longest length Ll was 13.4 μm, the shortest length Ls was 8 nm, the thickness of the particle layer was 0.9 μm, and the porosity of the particle layer was 4%. The carbon element ratio of the separation functional layer was 83.5 atomic %, the elastic modulus of the separation functional layer was 22 GPa, and the composite ratio of the separation functional layer and the particle layer was 16 volume %.

[0067] Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a frequency of peeling of 7 locations / m. The carbon dioxide gas permeation rate of the fluid separation membrane of Example 4 was "low," and the separation factor between carbon dioxide and methane was "excellent." The evaluation results are also shown in Table 1. (Example 5) A fluid separation membrane of Example 5 was produced in the same manner as Example 1, except that carbon nanotubes (CNT) with a large aspect ratio were used in the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 99% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 2592, the maximum length Ll was 24.1 μm, the minimum length Ls was 9 nm, the thickness of the particle layer was 0.8 μm, and the porosity of the particle layer was 35%. The carbon element ratio of the separation functional layer was 83.4 atomic %, the elastic modulus of the separation functional layer was 28 GPa, and the composite ratio of the separation functional layer and the particle layer was 22 volume %.

[0068] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 5 was "high," and the separation factor between carbon dioxide and methane was "good." The evaluation results are also shown in Table 1. (Example 6) A fluid separation membrane of Example 5 was produced in the same manner as Example 1, except that carbon nanotubes (CNT) with a large aspect ratio were used in the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 98% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 11040, the longest length Ll was 121.5 μm, the shortest length Ls was 11 nm, the thickness of the particle layer was 1.0 μm, and the porosity of the particle layer was 54%. In addition, the carbon element ratio of the separation functional layer was 83.3 atomic%, the elastic modulus of the separation functional layer was 25 GPa, and the composite ratio of the separation functional layer and the particle layer was 29% by volume.

[0069] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 6 was "high," and the separation factor between carbon dioxide and methane was "fair." The evaluation results are also shown in Table 1. (Example 7) A fluid separation membrane of Example 7 was produced in the same manner as Example 1, except that a slurry of graphene and carbon black (CB) mixed at a volume ratio of 9:1 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 92 volume %, the aspect ratio of the fibrous particles and / or tabular particles was 718, the longest length Ll was 2.8 μm, the shortest length Ls was 4 nm, the thickness of the particle layer was 0.7 μm, and the porosity of the particle layer was 18%. The carbon element ratio of the separation functional layer was 83.5 atomic %, the elastic modulus of the separation functional layer was 24 GPa, and the composite ratio of the separation functional layer and the particle layer was 14 volume %.

[0070] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 7 was "medium," and the separation factor between carbon dioxide and methane was "excellent." The evaluation results are also shown in Table 1. (Example 8) A fluid separation membrane of Example 8 was produced in the same manner as Example 1, except that a slurry of graphene and carbon black (CB) mixed at a volume ratio of 9:1 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 92% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 92, the longest length Ll was 0.8 μm, the shortest length Ls was 9 nm, the thickness of the particle layer was 0.8 μm, and the porosity of the particle layer was 19%. In addition, the carbon element ratio of the separation functional layer was 83.6 atomic%, the elastic modulus of the separation functional layer was 22 GPa, and the composite ratio of the separation functional layer and the particle layer was 17% by volume.

[0071] Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a peeling frequency of 5 locations / m. The carbon dioxide gas permeation rate of the fluid separation membrane of Example 8 was "medium," and the separation factor between carbon dioxide and methane was "excellent." The evaluation results are also shown in Table 1. (Example 9) A fluid separation membrane of Example 9 was produced in the same manner as Example 1, except that a slurry of graphene and carbon black (CB) mixed at a volume ratio of 9:1 was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 90% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 18, the longest length Ll was 0.3 μm, the shortest length Ls was 17 nm, the thickness of the particle layer was 0.8 μm, and the porosity of the particle layer was 22%. The carbon element ratio of the separation functional layer was 83.5 atomic %, the elastic modulus of the separation functional layer was 19 GPa, and the composite ratio of the separation functional layer and the particle layer was 20 volume %.

[0072] Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a peeling frequency of 14 locations / m. The carbon dioxide gas permeation rate of the fluid separation membrane of Example 9 was "medium," and the separation factor between carbon dioxide and methane was "good." The evaluation results are also shown in Table 2. (Example 10) The fluid separation membrane of Example 10 was produced in the same manner as Example 1, except that the carbon nanotube (CNT) particle layer was applied so as to be thin. Evaluation using the above-mentioned method revealed that the proportion of fibrous particles and / or tabular particles was 98% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1710, the longest length Ll was 26.6 μm, the shortest length Ls was 16 nm, the particle layer thickness was 0.4 μm, and the porosity of the particle layer was 25%. The carbon element ratio of the separation functional layer was 83.3 atomic %, the elastic modulus of the separation functional layer was 30 GPa, and the composite ratio of the separation functional layer and the particle layer was 24% by volume.

[0073] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 10 was "high," and the separation factor between carbon dioxide and methane was "good." The evaluation results are also shown in Table 2. (Example 11) A fluid separation membrane of Example 11 was produced in the same manner as Example 1, except that the carbon nanotube (CNT) particle layer was applied so as to be thin. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 100% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1674, the longest length Ll was 24.3 μm, the shortest length Ls was 15 nm, the thickness of the particle layer was 0.1 μm, and the porosity of the particle layer was 18%. In addition, the carbon element ratio of the separation functional layer was 83.4 atomic%, the elastic modulus of the separation functional layer was 28 GPa, and the composite ratio of the separation functional layer and the particle layer was 26% by volume.

[0074] Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a peeling frequency of 5 locations / m. The carbon dioxide gas permeation rate of the fluid separation membrane of Example 11 was "high," and the separation factor between carbon dioxide and methane was "good." The evaluation results are also shown in Table 2. (Example 12) The fluid separation membrane of Example 12 was produced in the same manner as Example 1, except that the carbon nanotube (CNT) particle layer was applied to a thicker layer. Evaluation using the above-described method revealed that the proportion of fibrous particles and / or tabular particles was 98% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1534, the longest length Ll was 19.8 μm, the shortest length Ls was 13 nm, the particle layer thickness was 12.4 μm, and the porosity of the particle layer was 28%. The carbon element ratio of the separation functional layer was 83.2 atomic %, the elastic modulus of the separation functional layer was 27 GPa, and the composite ratio of the separation functional layer and the particle layer was 22% by volume.

[0075] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 12 was "medium," and the separation factor for carbon dioxide and methane was "excellent." The evaluation results are also shown in Table 2. (Example 13) A fluid separation membrane of Example 13 was produced in the same manner as Example 1, except that the carbon nanotube (CNT) particle layer was applied to a thicker layer. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 95% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1552, the longest length Ll was 20.6 μm, the shortest length Ls was 13 nm, the thickness of the particle layer was 107.3 μm, and the porosity of the particle layer was 30%. In addition, the carbon element ratio of the separation functional layer was 83.5 atomic %, the elastic modulus of the separation functional layer was 28 GPa, and the composite ratio of the separation functional layer and the particle layer was 20% by volume.

[0076] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the fluid separation membrane of Example 13 had a carbon dioxide gas permeation rate of "low" and a separation factor of carbon dioxide and methane of "excellent." The evaluation results are also shown in Table 2. (Example 14) The fluid separation membrane of Example 14 was produced in the same manner as in Example 1, except that the porous material coated with an aromatic polyimide was used as a fluid separation membrane without being fired at 700°C in a nitrogen atmosphere. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 99% by volume, the aspect ratio of the fibrous particles and / or tabular particles was 1662, the longest length Ll was 19.5 μm, the shortest length Ls was 12 nm, the thickness of the particle layer was 0.9 μm, and the porosity of the particle layer was 28%. In addition, the carbon element ratio of the separation functional layer was 75.6 atomic%, the elastic modulus of the separation functional layer was 4 GPa, and the composite ratio of the separation functional layer and the particle layer was 20% by volume.

[0077] No peeling was observed at the interface between the porous support layer and the particle layer in the porous material, and the carbon dioxide gas permeation rate of the fluid separation membrane of Example 14 was "medium," and the separation factor between carbon dioxide and methane was "good." The evaluation results are also shown in Table 2. (Comparative Example 1) A fluid separation membrane of Comparative Example 1 was produced in the same manner as Example 1, except that a carbon black (CB) slurry was used instead of the carbon nanotube (CNT) slurry of Example 1. As a result of evaluation using the above-mentioned method, the proportion of fibrous particles and / or tabular particles was 0 vol%, the thickness of the particle layer was 0.8 μm, and the porosity of the particle layer was 6%. In addition, the carbon element ratio of the separation functional layer was 83.4 atomic %, the elastic modulus of the separation functional layer was 20 GPa, and the composite proportion of the separation functional layer and the particle layer was 28 vol%.

[0078] Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a peeling frequency of 23 locations / m. Peeling was observed between the porous material and the separation function layer in the fluid separation membrane of Comparative Example 1, and the membrane did not function as a fluid separation membrane. The evaluation results are also shown in Table 2. (Comparative Example 2) A fluid separation membrane of Comparative Example 2 was prepared in the same manner as in Example 1, except that a slurry of spherical silica microparticles was used instead of the carbon nanotube (CNT) slurry in Example 1. Evaluation using the above-described method revealed that the proportion of fibrous particles and / or plate-like particles was 0% by volume, the thickness of the particle layer was 1.0 μm, and the porosity of the particle layer was 25%. The carbon element ratio of the separation function layer was 83.2 atomic%, the elastic modulus of the separation function layer was 23 GPa, and the composite ratio of the separation function layer and the particle layer was 16% by volume. Peeling was observed at the interface between the porous support layer and the particle layer in the porous material, with a peeling frequency of 35 locations / m. In the fluid separation membrane of Comparative Example 2, peeling between the porous material and the separation functional layer was observed, and the membrane did not function as a fluid separation membrane.

[0079]

[0080]

[0081] The fluid separation membrane of the present invention can be suitably used in carbon dioxide separation and storage systems from exhaust gases of power plants, blast furnaces, etc., removal of sulfur components from gasified fuel gas in integrated coal gasification combined cycle power generation, purification of biogas and natural gas, and hydrogen purification from organic hydrides.

Claims

1. A gas separation membrane having a fibrous porous support layer whose surface is coated with a separation functional layer, wherein a particle layer is interposed in at least a part between the porous support layer and the separation functional layer, and the particle layer contains fibrous particles and / or plate-like particles.

2. The gas separation membrane according to Claim 1, wherein the proportion of carbon among the elements constituting the separation functional layer is 70 atomic % or more and 99.5 atomic % or less.

3. The gas separation membrane according to Claim 1, wherein the elastic modulus of the separation functional layer is 10 GPa or more and 300 GPa or less.

4. The gas separation membrane according to Claim 1, wherein the porous support layer is in the form of hollow fibers.

5. The gas separation membrane according to Claim 1, wherein the longest length Ll of the fibrous particles and / or the plate-like particles is 0.05 μm or more and 1000 μm or less.

6. The gas separation membrane according to Claim 1, wherein the aspect ratio of the fibrous particles and / or the plate-like particles is 20 or more and 10000 or less.

7. The gas separation membrane according to Claim 1, wherein the fibrous particles and / or the plate-like particles contain at least one selected from the group consisting of cellulose nanofibers, carbon nanohorns, carbon nanoribbons, carbon nanotubes, graphene, and graphene oxide.

8. A porous material having a fibrous porous support layer and a particle layer, wherein the particle layer is arranged so as to be in contact with at least a part of the surface of the porous support layer, and the particle layer is a porous material for a gas separation membrane containing fibrous particles and / or plate-like particles.

9. The porous material according to Claim 8, wherein the porous support layer is in the form of hollow fibers.

10. The porous material according to Claim 9, wherein the outer diameter of the hollow fiber-shaped porous support layer is 0.02 mm or more and 50 mm or less.

11. The porous material according to Claim 8, wherein the porosity of the porous support layer is 10% or more and 80% or less.

12. The porous material according to Claim 8, wherein the aspect ratio of the fibrous particles and / or the plate-like particles is 20 or more and 10000 or less.

13. The porous material according to Claim 8, wherein the porous support layer is made of an inorganic material.

14. The porous material according to Claim 8, wherein the porosity of the particle layer is 3% or more and 50% or less.

15. The porous material according to Claim 8, wherein the average thickness of the particle layer is 0.1 μm or more and 100 μm or less.

16. The porous material according to claim 8, wherein the shortest length Ls in the fibrous particles and / or the plate-like particles is 0.4 nm or more and 10 μm or less.

17. The porous material according to claim 8, wherein the fibrous particles and / or the plate-like particles contain at least one selected from the group consisting of cellulose nanofibers, carbon nanohorns, carbon nanoribbons, carbon nanotubes, graphene, and graphene oxide.

18. A method for producing a porous material for a gas separation membrane, comprising a step of bringing a slurry solution containing fibrous particles and / or plate-like particles into contact with a porous support layer to form a particle layer containing fibrous particles and / or plate-like particles on the outer surface of the porous support layer.

19. A method for producing a gas separation membrane, comprising a step of coating the porous material according to claim 18 with a solution containing a material for a fluid separation membrane and / or a precursor of a fluid separation membrane.

20. A separation membrane module having the gas separation membrane according to claim 1 in a case.

21. A gas separation process, characterized in that the separation membrane module according to claim 20 is arranged in at least a part of a process.

22. A method for producing a fluid, using at least in part the gas separation process according to claim 21.